Session: 12-07-01: Mechanics of Soft Materials
Paper Number: 95558
95558 - Constitutive Modeling of the Cross-Linked Polymers During the Trio-Aging Mechanism: Effects of Water, Oxygen, UV
Polymeric compounds are widely used in the modern era ranging from aerospace to packaging industries. Due to their applications in extreme conditions, they are largely susceptible to performance loss which is generally regarded as the aging phenomenon. Environmental factors such as oxygen, humidity, and UV radiation can induce different impacts on the service life of polymeric materials. It should be noted that these elements simultaneously exist in the real service life of a polymeric specimen which means they do have a synergized effect. While the solo impact of these elements is widely studied, there is still a wide gap in an investigation as well as modeling of aging of the polymeric component due to the concurrent exposure to the different environmental factors. In this paper, the effects of Hygrothermal, and Photo- Thermo oxidation aging (Trio-aging) on the mechanical response of elastomers are first investigated and then coupled to our previous model. Hygro-thermal aging itself is a competitive aging phenomenon that is due to hydrolytic (water) and thermo-oxidative (oxygen) aging. Here, we suggest that the synergized effects of deformation-induced damage, as well as diverse environmental conditions such as humidity, temperature, UV and oxygen, may be considered through a generic model by combining the concepts of network evolution, hygrothermal, and Photo-thermo oxidation paper. Similar to Hygro, Photo-thermo oxidation is also a dual aging mechanism which is due to the effects of UV radiation and oxygen in the elevated temperature. Here the main environmental elements are oxygen, water, and UV radiation which have a different micro-structural impact on the polymer matrix. While oxygen imposes chain scission and cross-link formation, water, and UV radiation mainly cause chain scission. Similar to our recent models, the dual network hypothesis of Topolosky is utilized and as a result, the strain energy of the polymer matrix is written in terms of two states namely unaged and infinity. The infinity state network, itself, is decomposed into three networks, namely brittle, flexible, and dead networks. While the brittle network models the cross-link formation as sub-structural phenomena, the flexible and dead networks are utilized to represent the chain scission. The contribution of these networks in the infinity state is based on the amount of relevant environmental elements. The model is developed for a domain with plenty of oxygen and holds true for a gradual aging process that happens in super-thin samples. Finally, the model is tested against a large number of sets of our experimental data. The model is an excellent candidate for advanced implementation in FE applications because of its interoperability, accuracy, and deep knowledge into the nature of the aging phenomena.
Presenting Author: Amir Bahrololoumi Michigan State University
Presenting Author Biography: A Ph.D. candidate with a strong background in Computational Mechanics, Multi-Physics Constitutive Modeling, Hands-on Experimental Characterization, and Polymer Degradation. Skilled in different programming languages like Matlab and Python, and microscopic and macroscopic computational mechanics simulation tools such as ABAQUS, and LAMMPS. Strong research professional with over \textbf{5 journal publications} and \textbf{6 conference proceedings} on different topics of computational mechanics.
Authors:
Amir Bahrololoumi Michigan State UniversityMamoon Shaafaey Michigan state University
Roozbeh Dargazany Michigan state university
Constitutive Modeling of the Cross-Linked Polymers During the Trio-Aging Mechanism: Effects of Water, Oxygen, UV
Paper Type
Technical Paper Publication